var app = angular.module('plunker', []);

app.controller('MainCtrl', function($scope) {
  $scope.register = function(){
    if($scope.demoForm.$valid)
      $scope.loggedin = true;
  }
});
<!DOCTYPE html>
<html ng-app="plunker">

  <head>
    <meta charset="utf-8" />
    <title>AngularJS Plunker</title>
    <link data-require="bootstrap-css@3.1.1" data-semver="3.1.1" rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css" />
    <script>document.write('<base href="' + document.location + '" />');</script>
    <link rel="stylesheet" href="style.css" />
    <script data-require="angular.js@1.2.x" src="https://code.angularjs.org/1.2.16/angular.js" data-semver="1.2.16"></script>
    <script data-require="jquery@*" data-semver="2.0.3" src="http://code.jquery.com/jquery-2.0.3.min.js"></script>
    <script data-require="bootstrap@*" data-semver="3.1.1" src="//netdna.bootstrapcdn.com/bootstrap/3.1.1/js/bootstrap.min.js"></script>
    <script src="app.js"></script>
  </head>

  <body ng-controller="MainCtrl" class="container">
    <div class="page-header">
      <h3>Simple validation <small>Angular forms</small></h3>
    </div>
    <form role="form" name="demoForm" ng-hide="loggedin" ng-submit="register()">
    
      <div class="form-group" ng-class="{'has-error': !demoForm.mail.$valid}">
        <input type="email" ng-model="email" name="mail" class="form-control" placeholder="Enter email" required>
        <span class="help-block" ng-show="demoForm.mail.$error.email">Please enter a valid email address</span>
      </div>
      
      <div class="form-group" ng-class="{'has-error': !demoForm.password.$valid}">
        <input type="password" ng-model="password" class="form-control" placeholder="Password" required ng-minlength="8" name="password">
        <span class="help-block" ng-show="demoForm.password.$error.minlength">Password must be at least 8 chars long</span>
      </div>
      
      <button type="submit" class="btn btn-primary">Register</button>
    </form>
    
    <div class="alert alert-success" ng-show="loggedin">You are now logged in</div>
    
  </body>

</html>
/* Put your css in here */